6 results
Cold Weather Application of Glyphosate for Garlic Mustard (Alliaria petiolata) Control
- Mark N. Frey, Catherine P. Herms, John Cardina
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- Journal:
- Weed Technology / Volume 21 / Issue 3 / September 2007
- Published online by Cambridge University Press:
- 20 January 2017, pp. 656-660
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Field studies were conducted from 2000 to 2002 to determine whether glyphosate applied during periods of low temperature (< 10 C) provides effective control of garlic mustard without injury to nontarget native herbs. A 1% glyphosate solution was applied on three dates between November and March in 2000 to 2001 and 2001 to 2002, when average daily temperatures ranged from −4.2 to 7 C. Glyphosate reduced the population density of prereproductive springtime garlic mustard infestations, regardless of application timing. During the primary bolting period (April to June), mortality of garlic mustard rosettes in sprayed plots was 87 to 94%, whereas mortality in nontreated plots was 12% in the first year and 41% in the second. Nontarget native herbaceous species were not injured by the cold-weather herbicide applications and exhibited higher springtime densities than in the nontreated plots. By targeting garlic mustard rosettes during the part of the year when most other plant species are dormant, managers can selectively control garlic mustard without damage to native herbs and, thereby, increase forest restoration success.
Phenological Indicators for Emergence of Large and Smooth Crabgrass (Digitaria sanguinalis and D. ischaemum)
- John Cardina, Catherine P. Herms, Daniel A. Herms
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- Journal:
- Weed Technology / Volume 25 / Issue 1 / March 2011
- Published online by Cambridge University Press:
- 20 January 2017, pp. 141-150
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We studied the emergence phenology of large and smooth crabgrass in lawn and bare soil environments and identified ornamental plants as phenological indicators that predict the progress of emergence. From 2002 to 2004, we monitored emergence of large and smooth crabgrass in field plots to estimate the dates of first emergence, and 25, 50 and 80% emergence. Each year, we monitored 74 taxa of ornamental plants to determine dates of first and full bloom. We compiled dates of weed emergence and ornamental blooming to create a biological calendar of phenological events for each year, ordered by average cumulative degree days (DD) (January 1 start date, 10 C base temperature). Ornamental plant flowering events that occurred in a regular sequence before crabgrass emergence events were identified as the phenological indicators. We also evaluated DD and rule-based models for predicting crabgrass emergence and optimum time of PRE herbicide application. In general, smooth crabgrass reached each emergence stage earlier than large crabgrass. Differences in emergence between environments were not consistent over years for the two species. There was no consistent pattern in parameters for DD models predicting emergence events for either crabgrass species or environment. For published DD models, the deviation between observed and predicted emergence events ranged from 0 to > 60 d. Published rule-based predictions, though accurate in some cases, were sometimes difficult to implement. The order of ornamental plant blooming and crabgrass emergence events was generally consistent over years (R2 = 0.977). The biological calendar provided useful crabgrass emergence predictions using real-time field-based indicators of sequential biological events that can help managers plan and optimize management strategies.
Evaluating Phenological Indicators for Predicting Giant Foxtail (Setaria faberi) Emergence
- John Cardina, Catherine P. Herms, Daniel A. Herms, Frank Forcella
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- Journal:
- Weed Science / Volume 55 / Issue 5 / October 2007
- Published online by Cambridge University Press:
- 20 January 2017, pp. 455-464
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We evaluated the use of ornamental plants as phenological indicators for predicting giant foxtail emergence and compared their performance with predictions based upon Julian day, cumulative growing degree–days (GDD), and the WeedCast program. From 1997 to 2001, we monitored giant foxtail emergence in a field experiment with and without fall and spring tillage to estimate the dates of 25, 50, and 80% emergence; we also recorded dates of first and full bloom of 23 ornamental plant species. Dates of weed emergence and ornamental blooming for 1997 to 2000 were compiled in a phenological calendar consisting of 54 phenological events for each year, and events were ordered by average (1997 to 2000) cumulative GDD (January 1 start date, 10 C base temperature). Bloom events occurring just before the giant foxtail emergence events were chosen as the phenological indicators for 2001. The Julian day method used the average (1997 to 2000) dates of foxtail emergence to predict 2001 emergence. The GDD model (October 1 start date, 0 C base temperature) was chosen by determining the combination of start date and base temperature that provided the lowest coefficient of variation for the 1997 to 2000 data. The WeedCast prediction was generated using local soil and environmental data from 2001. The rank order of the 54 phenological events in 2001 showed little deviation from the 4-yr (1997 to 2000) average rank order (R2 = 0.96). The phenological calendar indicated that, on average, 25% of giant foxtail seedlings had emerged when red chokeberry was in first bloom, and 80% of seedlings had emerged around the time multiflora rose was in full bloom. We compared the phenological calendar predictions for 25, 50, and 80% emergence with those based on Julian day, cumulative GDD, and WeedCast. The average deviation in predictions ranged from 4.4 d for the phenological calendar to 11.4 d for GDD. In addition to being generally more accurate, the phenological calendar approach also offers the advantage of providing information on the order of phenological events, thus helping to anticipate the progress of emergence and to plan and implement management strategies.
Weed seedbank community composition in a 35-yr-old tillage and rotation experiment
- Lynn M. Sosnoskie, Catherine P. Herms, John Cardina
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- Journal:
- Weed Science / Volume 54 / Issue 2 / April 2006
- Published online by Cambridge University Press:
- 20 January 2017, pp. 263-273
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Knowledge about how the type, timing, and arrangement of cultural practices influence weed species composition is important for understanding the ecological results of control strategies and designing alternative crop management systems. We evaluated weed seed density, diversity, and community composition from 1997 to 1999 in a 35-yr-old study comparing cropping sequences (continuous corn, corn–soybean, corn–oat–hay) and tillage systems (conventional, minimum, and no-tillage) in Wooster, OH. Weed seedbank diversity, as measured by species richness (S), evenness (J), and the Shannon–Weiner index (H′), was influenced by crop diversity; mean values for each of the indices were generally higher for all combinations of the three-crop sequence than for the corn monoculture or the corn–soybean rotation. Except for 1998, mean seed density (to a depth of 10 cm) was higher in continuous corn than in corn and soybean rotations Species richness and seed density were also affected by tillage. Mean values for and mean germinable seeds were greatest in the no-tillage system, where the soil was disturbed only by the coulter units of the planter. Differences in weed seedbank community composition among tillage and rotation treatments were examined using two multivariate analyses. Using a multiresponse permutation procedure and canonical discriminant analysis, results suggest that the weed seed community in a corn–oat–hay rotational system differs in structure and composition from communities associated with continuous corn and corn–soybean systems. Additionally, germinable weed seed communities in no-tillage differed in composition from those in conventional and minimum tillage. Crop sequence and tillage system influenced weed species density and diversity and therefore community structure. Manipulation of these factors could help reduce the negative impact of weeds on crop production.
Seedbank and Emerged Weed Communities Following Adoption of Glyphosate-Resistant Crops in a Long-Term Tillage and Rotation Study
- Lynn M. Sosnoskie, Catherine P. Herms, John Cardina, Theodore M. Webster
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- Journal:
- Weed Science / Volume 57 / Issue 3 / June 2009
- Published online by Cambridge University Press:
- 20 January 2017, pp. 261-270
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The compositions of the germinable weed seedbank and aboveground weed communities in a long-term tillage and rotation study were characterized 4, 5, and 6 yr (2002 to 2004) after the adoption of glyphosate-tolerant corn and soybean. Averaged across rotation, mean germinable weed seed density and diversity were greatest in the no-tillage treatment as compared to the minimum- and conventional-tillage treatments. Averaged over tillage, density and diversity were greater in the corn–oat–hay (ryegrass + alfalfa) system as compared to the continuous corn and corn–soybean rotations. Similar trends in density and diversity were observed for the aboveground weed communities. Differences in community composition among treatments were quantified with the use of a multiresponse permutation procedure. Results indicated that the weed seedbank community in a corn–oat–hay rotational system differed from the communities associated with the continuous corn and corn–soybean rotational systems. Weed seedbank communities developing under a no-tillage operation differed from those in minimum- and conventional-tillage scenarios. Compositional differences among the aboveground weed communities were less pronounced in response to tillage and rotation. Indicator species analyses indicated that the number of significant indicator weed species was generally higher for no tillage than minimum or conventional tillage for both the seedbank and the aboveground weed communities. The number of significant indicator species for the seedbank and weed communities was generally greater in the three-crop rotation as compared to the continuous corn and corn–soybean rotations. The trends observed in density, diversity, and community composition after the adoption of glyphosate-tolerant corn and soybeans, and a glyphosate-dominated weed management program, were also observed when soil-applied herbicides were included in the study. We suggest that the switch to a POST-glyphosate protocol did not significantly alter weed communities in the short term in this study.
Crop rotation and tillage system effects on weed seedbanks
- John Cardina, Catherine P. Herms, Douglas J. Doohan
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- Journal:
- Weed Science / Volume 50 / Issue 4 / August 2002
- Published online by Cambridge University Press:
- 20 January 2017, pp. 448-460
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We characterized the size and species composition of the weed seedbank after 35 yr of continuous crop rotation and tillage system treatments at two locations in Ohio. Spring seedbanks were monitored during 1997, 1998, and 1999 in continuous corn (CCC), corn–soybean (CS), and corn–oats–hay (COH) rotations in moldboard plow (MP), chisel plow (CP), and no-tillage (NT) plots where the same herbicide was used for a given crop each growing season. There were 47 species at Wooster and 45 species at Hoytville, with 37 species occurring at both locations in all 3 yr. Crop rotation was a more important determinant of seed density than was tillage system. Seed density was highest in NT and generally declined as tillage intensity increased. Seeds accumulated near the surface (0 to 5 cm) in NT but were uniformly distributed with depth in other tillage systems. At both locations there was a significant interaction between tillage and rotation for estimates of the total seed density. Seed density was highest in NT-CCC, with 26,850 seeds m−2 at Wooster and 8,680 seeds m−2 at Hoytville. At Wooster total seed density in CCC plots was 45 and 60% lower than in COH plots for CP and MP. In NT the total seed density was 40% greater in CCC than in COH. At Hoytville total seed density in CCC plots was 72% lower than in COH plots that were CP or MP, whereas seed density was 45% higher in CCC than in COH plots that were in an NT system. There were more significant differences in seedbank density for any given species for crop rotation than for tillage treatments. Seed densities of three broadleaves (shepherd's-purse, Pennsylvania smartweed, and corn speedwell) at Wooster and four broadleaves (yellow woodsorrel, redroot pigweed, Pennsylvania smartweed, and spotted spurge) at Hoytville were more abundant in COH (140 to 630 seeds m−2) than in CS (10 to 270 seeds m−2) or CCC (< 1 to 60 seeds m−2), regardless of the tillage system. At both locations Pennsylvania smartweed seeds were more abundant in COH (260 and 630 seeds m−2) than in other rotations (10 to 20 seeds m−2). Relative importance (RI) values, based on relative density and relative frequency of each species, were lower in CS than in CCC for common lambsquarters and five other weeds at Wooster; RI of giant foxtail was 80% lower in COH than in CCC at Hoytville. The data show how species composition and abundance change in response to crop and soil management. The results can help to determine how complex plant communities are “assembled” from a pool of species by specific constraints or filters.